Interactions between bovine papilloma virus (BPV) and viral transformed cells will be examined. BPV DNA will be characterized by analysis of restriction endonuclease cleavage patterns and a physical map of the viral genome constructed. Labeled BPV DNA will be employed to screen animal tumors suspected of BPV etiology for BPV-specific DNA sequences by analysis of nucleic acid reassociation kinetics. Labeled BPV DNA will be used to determine the extend of integration of the BPV genome in BPV transformed cells.